Viewed technically, most stick formulations are anhydrous fatty mixtures of solid or semi-solid waxes and liquid oils, where the highly purified paraffin oils and waxes represent the lipstick base mass. Water-containing preparations are also known, which are also sometimes in the form of water-in-oil emulsions.
Customary base substances of the prior art for stick-like preparations are, for example, liquid oils (e.g. paraffin oils, castor oil, isopropyl myristate), semi-solid constituents (e.g. Vaseline, lanolin), solid constituents (e.g. beeswax, ceresin and microcrystalline waxes or ozokerite), and high-melting waxes (e.g. carnauba wax, candelilla wax).
The disadvantage of sticks for face and cheeks known hitherto is firstly the inadequate stability of the sticks. Many sticks are sensitive to shear forces, and crumble easily, meaning that the decorative emulsion cannot be distributed on the skin very easily. In addition, they are not particularly temperature-stable, smear and run upon use in the hot summer months, while in winter at cold temperatures they become brittle and dull.
Also, the sensory properties have hitherto left something to be desired. The sticks should actually have a pleasant cooling effect on the skin and feel creamy, which is only achieved in part with the products according to the prior art.
Standard commercial antiwrinkle products are in most cases lotions, creams, gel creams, which have a content of active ingredients for reducing the wrinkling of skin. It would be desirable to be able to apply these active ingredients in a targeted manner to the affected areas of the skin. Suitable for this purpose are stick formulations, although currently these are known in the market only in the form of lipcare sticks, foundation sticks and the like, and are not conceived for the reduction or prophylaxis of wrinkles. Such sticks would be advantageous since they could be applied in a targeted manner to areas around the corners of the mouth or in the eye and forehead area. In addition, it can be expected that the applied stick ingredients spread to a lesser degree on the skin, which could be advantageous particularly in the eye area.
Even when pressed lightly, a cosmetic stick should give them a nongreasy, dull or sticky, but nevertheless well-adhering fatty film. This fatty film then makes the lips or the skin smooth and supple.
The skin of the lips has only an extremely thin horny layer. There are no sweat glands on the lips, and only a few sebaceous glands. The skin on the lips is therefore virtually free from lipids and is prone to drying out, particularly in cold and dry weather. It is possible for small cracks to form in the skin, and the susceptibility of the lips to chemical, physical and microbial effects (e.g. of foods, sunlight, Herpes simplex viruses) increases.
The aim of lipcare sticks is to prevent this. These products usually contain a high content of waxes and fatty components which form a covering layer over the lips following application.
The preparations for lipcare sticks can additionally have incorporated into them active ingredients which are required for lipcare or lip protection, for example vitamins, moisturizing agents, photoprotective agents, concealing pigments etc.
The dermis of the lips has papillae which have a good blood supply and extend up to just under the surface of the lips. For this reason, the lips are reddish in color and, depending on the coloring of the person in question, distinguished from the other facial skin in terms of color to a greater or lesser degree. A styling means of decorative cosmetics is then also to match the lip color to the type of person through appropriate cosmetics.
Products of this type are decorative lipsticks into which a very wide variety of color pigments can be incorporated. These sticks too comprise high contents of waxes and fatty components which form a covering lipid layer over the lips following application.
However, the object of this layer is not primarily to protect the lip skin from drying out. The lipid layer here serves as a base for the incorporated pigment substances which adheres to the lips; the pigments themselves cannot be applied to the lips without such a base for many reasons.
It is also possible to combine the properties of care and decorative lipsticks together, i.e. to incorporate care or protecting substances into decorative lipsticks.
Acne is a skin disorder with various forms and causes, characterized by uninflamed and inflamed bumps, originating from blocked hair follicles (comedones) which can lead to the formation of pustules, abscesses and scars. The most frequent form is Acne vulgaris, which occurs primarily in puberty. Causative conditions of Acne vulgaris are the keratinization and blocking of the hair follicle opening, the production of sebum, which is dependent on the level of male sex hormones in the blood, and the production of free fatty acids and tissue-damaging enzymes by bacteria (Propionibacterium acnes).
Antiacne active ingredients such as octoxyglycerol are described, for example, in U.S. Pat. No. 6,040,347 and DE 4240674. Although sticks are also mentioned there as a conceivable application form, anhydrous fatty sticks are to be understood by this. The advantages of formulating the active ingredient in a water-containing W/O stick was not recognized.
Lipcare sticks in most cases comprise a high content of waxes and fatty components which, following application, form a covering layer over the lips. The preparations for lipcare sticks can additionally have incorporated into them active ingredients which are required for lipcare or lip protection, for example vitamins, moisturizing agents, photoprotective agents, concealing pigments etc.
Lipsticks of the prior art with a content of paraffins and beeswax are described in “Kosmetik, Entwicklung Herstellung und Anwendung kosmetischer Mittel” [Cosmetics, development, preparation and use of cosmetic compositions], p. 105, Editor: W. Umbach, Georg Thieme Verlag, Stuttgart—New York, 1988.
Since both care and also primarily decorative lipsticks of the prior art have in some instances serious shortcomings, an object of the present invention was to overcome these shortcomings.
Due to the high sensitivity of the lip area, in particular toward ultraviolet radiation as a consequence of the virtually complete lack of pigments, it is advisable, especially in cases of increased UV exposure, such as in high mountains, to provide the lip area with protection against UV radiation in the form of corresponding stick-like photoprotective preparations. Inorganic pigments are often used particularly in stick-like preparations of the prior art as UV absorbers or UV reflectors for protecting the lip area against UV rays. These are, in particular, oxides of titanium, but also sometimes of zinc, iron, zirconium, silicon, manganese, aluminum, cerium and mixtures thereof, and also modifications.
A considerable shortcoming of the formulations of the prior art is, inter alia, that, due to the low water contents of per se acceptable emulsion sticks, it is virtually impossible to incorporate water-soluble UV filter substances into such formulations. It was thus a further object of the present invention to make available sticks with exclusively water-soluble UV filters or water-dispersible pigments (for example titanium dioxide), or combinations of water-soluble and fat-soluble UV filters and pigments.
The prior art has other disadvantages. These include the fact that water-soluble active ingredients are often not sufficiently fat-soluble to be incorporated into the cosmetic bases to a noteworthy degree. On the other hand, a certain water content would be entirely desired in order to increase the compatibility of the cosmetic stick with the human skin. In addition, it is therefore not possible to make sticks with very high water contents in accordance with the prior art because the water is incompatible with the hydrophobic oil/wax/emulsifier matrix.
Sticks which, besides relatively large amounts of water, additionally comprise relatively large concentrations of water-soluble active ingredients, high concentrations of skin-moisturizing agents (3-50% of glycerol, for example) and of fat-soluble active ingredients are not described. Although sticks with relatively large amounts of water are known, active moisturizing of the skin, which should, in addition, last for a relatively long time and have biophysically measurable moisturizing values like a classic O/W or W/O emulsion is unknown. This is probably due to the fact that only extremely short-term moisturizing is brought about by water. In addition, low-water or anhydrous stick formulations are only therefore passively moisturizing because occlusive waxes are used which cause a build-up of water in the skin. Active moisturizing by a hydrolipid film comprising water which additionally comprises relatively large amounts of skin-moisturizing agents instead of an occlusive lipid film or of an only water-containing stick has hitherto not been described as advantageous. However, such sunscreen or aftersun sticks would be advantageous since active ingredient-containing hydrolipid films could then form instead of lipid films. In addition, the waxes used could additionally cause occlusive effects, as in the case of anhydrous sticks, resulting in a synergism from water, moisturizing agent and wax for emulsion sticks designed in this way.
In addition, it was hitherto not known that water-containing sticks can additionally comprise concealing pigments, or else combinations of concealing pigments and pearlescent pigments or exclusively pearlescent pigments. Pearlescent pigments are, for example, therefore difficult to integrate into water-containing formulations because they are shear-sensitive, meaning that the pearlescent effect fails to appear or only unstable formulations arise. In addition, the pigments used generally have to be made compatible with the water/moisturizing agent/lipid/wax matrix.
According to the ideal profile of requirements, cosmetic or dermatological sticks should be able to be applied smoothly and without great friction resistance. Moreover, such a formulation must also satisfy the requirements that the stick in question must be fracture-resistant and temperature-resistant and the formulation must not lose oil.
If cosmetic or pharmaceutical sticks are to contain certain active ingredients, it is conceivable that the other constituents are incompatible with the active ingredients. This is the case particularly frequently when the cosmetic sticks are intended to be used as sunscreen sticks or aftersun sticks, when water-soluble photoprotective filters are to be present in the stick in relatively large amounts, when, for the preparation of a prophylactic antiwrinkle stick or of an antiwrinkle stick, water-soluble active ingredients are to be incorporated in amounts known to the person skilled in the art, when, for the preparation of an antiacne stick, water-soluble antiacne active ingredients are to be incorporated in amounts known to the person skilled in the art, when water-soluble skin-moisturizing agents are to be present in the stick in relatively large amounts or when, for the preparation of a stick, further fat- or water-soluble active ingredients, such as pigments, pearlescent pigments, vitamins and/or antioxidants, are to be additionally incorporated.
For an antiacne stick, for example, it would, however, be particularly advantageous if the content of fat-soluble constituents were as low as possible.
Pearlescent pigments are difficult to integrate into water-containing formulations because they are shear-sensitive, meaning that the pearlescent effect fails to appear or only unstable formulations arise. In addition, the pigments used generally have to be made compatible with the water/moisturizing agent/lipid/wax matrix.
Admittedly, both WO 98/17232 and EP 1 064 908 describe cosmetic and dermatological sticks with a high water content where, in the former, the emulsifier system according to the invention is also described and, in the latter, the use of pigments.
The most important ingredient of a stick is the pigments, which have to be stabily incorporated into the system and represent the color-imparting component. The incorporation of pigments into emulsion sticks may result in various instabilities. In mild cases, these are color inhomogeneities, where the different pigments are not distributed evenly within the stick. In more serious cases, instabilities in the stick system may arise where temperature stability and stability to breaking are impaired.
For this reason, it is important for an appealing stick (sensorally attractive, optically flawless and stable) that all of the components of the system are matched to one another.
This includes both the combination of the pigments and fillers and suitable selection of emulsifiers, waxes and oils.
The specifications cited above were unable to point the way to the present invention since the sticks mentioned therein are not sticks (foundation sticks) whose contents are applied over a large area on the face. The stability of the sticks according to the invention is also far superior to that of those described hitherto. They are considerably less sensitive to shear forces and remain stable and spreadable within the entire temperature range from −10° C. to 53° C. Above all, the sensory properties of the sticks according to the invention differ from those which are disclosed in the specifications cited above.
DE 23 35 549 discloses a process for the preparation of a cosmetic stick based on a W/O emulsion. According to this teaching, a gel is prepared from a polyhydroxy compound and a nonionogenic, surface-active compound; this is mixed with a cosmetic base, and water is emulsified into the mixture.
DE 41 28 748 describes cosmetic sticks which are characterized in that they represent emulsions and comprise, as essential constituents, beeswax, one or more esters of a saturated carboxylic acid having 20-40 carbon atoms and a saturated alcohol having 14-34 carbon atoms, water, and optionally further lipids and/or customary auxiliaries and additives.
U.S. Pat. No. 4,719,103 describes an antiperspirant stick based on a W/O emulsion which has a high water content, which is characterized by a content of volatile silicone components, a solid alkanol, and polyglycerol fatty acid esters, for example polyglyceryl isostearate, as emulsifier. U.S. Pat. No. 4,704,271 and U.S. Pat. No. 4,725,431 describe similar preparations.
EP 0748622 describes sticks containing volatile oils, water-repelling polymers which are soluble in the volatile oil, and nonvolatile oils and powder ingredients.
GB 2162439 describes paraffin-containing sticks which reportedly have a high water content, the emulsifier being chosen from the group of metal salts.
DE 19643237 describes cosmetic sticks which are characterized by a relatively high water content. These comprise, inter alia, certain wax and oil components, certain W/O emulsifiers, besides 30 to 85% by weight of water. The use of relatively large amounts of skin-moisturizing agents is not described, only the use of 2% by weight of glycerol is disclosed in the examples.
DE 29919474 describes W/O emulsion sticks. By using polysaccharides, a three-dimensional structure is produced which reportedly confers more stability to the sticks. The use of large amounts of skin-moisturizing agents also in the presence of pigments is not described. Also, the omission of polysaccharides while retaining the stick structure is not regarded as being advantageous.
DE 20009445 claims sticks which comprise only small amounts of water (25%). Nothing is stated concerning skin-moisturizing agents.
EP 1064908 describes emulsion sticks which comprise only very small water contents (14%, p. 4, Ex. 3). The content of skin-moisturizing agents is 9% (glycerol, butylene glycol, sorbitol). For the use in antiacne products in particular, a particularly low content of oils or lipids would, by contrast, be advantageous since these counteract the healing of the acne.
EP 0194887 describes the use of ethoxylated waxes and also triglyceride waxes for the preparation of anhydrous sticks.
WO 9817232 and describe lipsticks which are characterized by a relatively high content of water. Since besides the described cooling effect, the substantivity (for example upon use of colored pigments or pearlescent pigments) for certain sticks, which additionally reportedly comprise relatively large amounts of skin-moisturizing agents, is also important, it was discussed further in the specification.
This has also not been explained in the invention which is described above. In addition, it has hitherto not been mentioned that cosmetic sticks can also be prepared in the presence of triglyceride waxes or ethoxylated waxes.
A considerable shortcoming of the formulations of the prior art is, inter alia, that, due to the low water contents of perfectly acceptable emulsion sticks, it was virtually impossible to incorporate water-soluble antiacne active ingredients into such formulations. For example, water-soluble or dispersible active ingredients, such as lactic acid, salicylic acid, short-chain mono-, di- and triglycerol esters (C8-12 fatty acids), aluminum salts, glycerol ethers, zinc compounds, alkyl-branched fatty acids, can only be incorporated with difficulty as antiacne active ingredients in accordance with the prior art.
A considerable shortcoming of the formulations of the prior art is, inter alia, that, due to the low water contents of per se acceptable emulsion sticks, it was virtually impossible to incorporate water-soluble antiwrinkle active ingredients into such formulations. In addition, there is a shortcoming in combining water-soluble or fat-soluble active ingredients. For example, water-soluble or dispersible active ingredients, such as vitamin C, carnitine, lipoic acid, alpha-hydroxy acids, can only be incorporated with difficulty as antiwrinkle active ingredients in accordance with the prior art.
Pearlescent pigments are difficult to integrate into water-containing formulations because they are shear-sensitive, meaning that the pearlescent effect fails to appear or only unstable formulations arise. In addition, the pigments used generally have to be made compatible with the water/moisturizing agent/lipid/wax matrix.